If the temperatures are increasing in a mountainous region, in order to be sure in that, the evidence can simply be obtained by the vegetation. The mountains tend to be warmer at the lower parts, and as the elevation increases, the temperature decreases. If it is a higher mountain, then we will see that there is certain type of vegetation in the lower parts, above it a belt of another vegetation type, above that one there's usually a belt of grasses, and the highest parts are usually with little to no vegetation. If the temperature increases though, then the vegetation from the bottom will start moving upwards, occupying larger portion, the second layer will move upwards as well, and the grasses will come around the top part of the mountain, with the barren part disappearing from the scene.
Changes in the pressure create the flow of the air to move up and down in the ear and thus create popping sound.
Explanation:
The ear-popping is caused by the phenomenon of the opening of the Eustachian tube when one swallows and it might be automatically when you blow our nose or are setting in an airplane and this sound is created when the air enters the middle ear through the tube.